Solar storm of 1859

Sunspots of September 1, 1859, as sketched by Richard Carrington. A and B mark the initial positions of an intensely bright event, which moved over the course of five minutes to C and D before disappearing.

Studies have shown that a solar storm of this magnitude occurring today would likely cause widespread problems for modern civilization. The solar storm of 2012 was of similar magnitude, but it passed Earth's orbit without striking the Earth.[2]

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From August 28 through September 2, 1859, numerous sunspots were observed on the Sun. On August 29, southern aurorae were observed as far north as Queensland, Australia.[3] Just before noon on September 1, the English amateur astronomers Richard Carrington and Richard Hodgson independently made the first observations of a solar flare.[4] The flare was associated with a major coronal mass ejection (CME) that travelled directly toward Earth, taking 17.6 hours to make the 93 million mile journey. It is believed that the relatively high speed of this CME (typical CMEs take several days to arrive at Earth) was made possible by a prior CME, perhaps the cause of the large aurora event on August 29, that "cleared the way" of ambient solar windplasma for the Carrington event.[4]

On September 1–2, 1859, one of the largest recorded geomagnetic storms (as recorded by ground-based magnetometers) occurred. Aurorae were seen around the world, those in the northern hemisphere even as far south as the Caribbean; those over the Rocky Mountains were so bright that their glow awoke gold miners, who began preparing breakfast because they thought it was morning.[4] People who happened to be awake in the northeastern US could read a newspaper by the aurora's light.[5] The aurora was visible as far from the poles as Cuba and Hawaii.[6]

Telegraph systems all over Europe and North America failed, in some cases giving telegraph operators electric shocks.[7] Telegraph pylons threw sparks.[8] Some telegraph operators could continue to send and receive messages despite having disconnected their power supplies.[9]

On Saturday, September 3, 1859, the Baltimore American and Commercial Advertiser reported, "Those who happened to be out late on Thursday night had an opportunity of witnessing another magnificent display of the auroral lights. The phenomenon was very similar to the display on Sunday night, though at times the light was, if possible, more brilliant, and the prismatic hues more varied and gorgeous. The light appeared to cover the whole firmament, apparently like a luminous cloud, through which the stars of the larger magnitude indistinctly shone. The light was greater than that of the moon at its full, but had an indescribable softness and delicacy that seemed to envelop everything upon which it rested. Between 12 and 1 o'clock, when the display was at its full brilliancy, the quiet streets of the city resting under this strange light, presented a beautiful as well as singular appearance."[10]

In June 2013, a joint venture from researchers at Lloyd's of London and Atmospheric and Environmental Research (AER) in the United States used data from the Carrington Event to estimate the current cost of a similar event to the US alone at $0.6–2.6 trillion.[11]

Ice cores containing thin nitrate-rich layers have been analyzed to reconstruct a history of past solar storms predating reliable observations. Data from Greenland ice cores, gathered by Kenneth G. McCracken[12] and others, show evidence that events of this magnitude—as measured by high-energy proton radiation, not geomagnetic effect—occur approximately once per 500 years, with events at least one-fifth as large occurring several times per century.[13] However, more recent work by the ice core community (McCracken et al. are space scientists) shows that nitrate spikes are not a result of solar energetic particle events, so use of this technique is in doubt. 10Be and 14C are considered to be more reliable indicators by the ice core community.[14] These similar but much more extreme cosmic ray events, however, may originate outside the solar system and even outside the galaxy. Less severe storms have occurred in 1921 and 1960, when widespread radio disruption was reported. The March 1989 geomagnetic storm knocked out power across large sections of Quebec. On July 23, 2012 a "Carrington-class" Solar Superstorm (Solar flare, Coronal mass ejection, Solar EMP) was observed; its trajectory missed Earth in orbit. Information about these observations was shared first publicly by NASA on April 28, 2014.[2][15]